Mobility is the result of the body being capable of transporting itself. This seemingly simple capability covers a multitude of complex factors that contribute to it in various degrees. The cardiovascular system needs to be in good order to ensure the adequate oxygenation of the muscle groups that work and the transportation of nutrients to them as well as the removal of biochemical byproducts. The aerobic system has to work to ensure that oxygen inhaled from the air is dissolved in the bloodstream and CO2 is removed. Tendons have to lift muscles and ligaments that connect different muscle groups need to work in tandem with the tendons. Everything needs to happen in the right order so that the body's kinetic chains work in a smooth, flowing motion that preserves the transfer of energy from the foot hitting the ground. And that's before we start to think about things like muscle strength, bone density, short and long action fiber ratio in the make up of the muscle and the ratio of body weight to muscle mass. Is it any wonder then that we need a monthly challenge to help us get better at moving our body about?